Wiki info about F4U-1D

When designing the single-engine carrier-based fighter-bomber designated as the Chance Vought F4U-1D Le Corsaire (“The Corsair”), it was decided to ignore the new weaponry from the F4U-1C and use six of the proven 12.7 mm machine guns (as had been on the F4U-1A).
The plane’s main innovation was its capacity to hold two 454-kg bombs and one 907-kg bomb. Thus, the F4U-1D could be used as a heavy fighter-bomber. Also, additional fuel tanks could be installed instead of bombs. In addition, a more powerful engine was added, and the last 266 F4U-1Ds and 295 FG-1Ds could carry eight 127-millimeter HVAR rockets.
The F4U-1D, the first large-scale variant after the F4U-1A, was produced not only at Chance Vought factory, but also at the Goodyear factory. Planes from the latter became known as FG-1Ds. The Brewster plant, which had produced the F4U-1A, did not work on the production of this variant, as its contract was annulled.
All in all, 1685 F4U-1Ds were made at the Chance Vought factory and 1997 FG-1Ds at the Goodyear factory.